[LICM] Preserve Disjoint flag on OR when hoisting. (#140266)

Update hoistBOAssociation to preserve Disjoint flags on the newly
created instructions if both ORs are disjoint.

Fixes https://github.com/llvm/llvm-project/issues/139625.

PR: https://github.com/llvm/llvm-project/pull/140266

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index 62ef40c..7d89a13 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2877,6 +2877,13 @@ static bool hoistBOAssociation(Instruction &I, Loop &L,
     if (auto *I = dyn_cast<Instruction>(Inv))
       I->setFastMathFlags(Intersect);
     NewBO->setFastMathFlags(Intersect);
+  } else if (Opcode == Instruction::Or) {
+    bool Disjoint = cast<PossiblyDisjointInst>(BO)->isDisjoint() &&
+                    cast<PossiblyDisjointInst>(BO0)->isDisjoint();
+    // If `Inv` was not constant-folded, a new Instruction has been created.
+    if (auto *I = dyn_cast<PossiblyDisjointInst>(Inv))
+      I->setIsDisjoint(Disjoint);
+    cast<PossiblyDisjointInst>(NewBO)->setIsDisjoint(Disjoint);
   }
 
   BO->replaceAllUsesWith(NewBO);